Idlers Tight with Belt

I just moved and rebuilt a Shapeoko 3 XXL. During one of the last steps of squaring the machine, I noticed that when I push the X-axis to the back of the machine, there’s a resistance where the idlers meet the 2" length of belt doubled up. I have to use considerably more force to push back to the endplates. Then, there’s resistance in coming forward till it gets past the double belt and it suddenly jumps forward. The teeth of the belt are interlocked as suggested. Not sure if this happened during my first build, but it seems like it could be problematic when homing the machine or cutting at the rear. Is this normal?

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You may need to trim the belt overlap a bit shorter — but first try loosening the bolt for the idlers, pushing them up/out and then retightening.


Also check that your v-wheels aren’t rubbing against belt clips, I could see that causing significant drag. I put a tiny crescent wrench on the belt clip and turn it “away” from the V-wheels while tightening the tension bolt.

That will happen right around the same time your idlers roll onto the overlap.


Thanks for your quick replies!

Loosening the idler bolts didn’t seem to do anything; there’s not much wiggle room there. I did adjust the belt overlap, but I didn’t cut it. I shortened the backside to 1" and extended the frontside to 3". This seems to alleviate the problem with resistance. Those overlaps are actually the ‘exact’ dimensions front and back to avoid the idler interference on both ends. I know the instruction booklet is constantly being edited, but maybe this would be a good edit to indicate for Y1 & Y2. Or just shorten the length of all belts by 2" and make the overlap 1" everywhere. Any reason it’s a 2" overlap to begin with?

Good suggestion. I noticed that too with my first build and twerked the clips away. Ultimately it was the idlers.

Happy Cutting. Thanks!


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